Ketosilanes



April 14, 1953 L. H. SOMMER KEITOSILANES Filed Jan. 5, 1951 @mh-Omni:

mrooo-10 E ou :u oomro Y NGow m NOU NIU Y mmmuxm INVENTOR. E0 H. 50M/WER mz im oufuoofu x W N m T T A Patented Apr. 14, i953 UNITED .STATES PATENT .oiFFflcE .Leo H. Sommer, .Gambridge, Mass., assigner :to .Dow .Coming .Corporatiom Midlandl ."Mich., `a

`.corporationof.Michigan acorn) zsieHX y acetoacetic -ester inethanol lin 'accordance `with the conditionsmormally employed in organic synthesis. The product Aobtained by tliis'rea'ction willv'aiy, depending upon whether an `excess of sodium or an vexcess oigaceto'aceticfester Lis employed. The various reactions involved'are shown in the drawing. n Y

'The' 'drawing is -a .iioW sheets'howing the various 4"reactions involved in the i preparationV of Where "X is halogen `with the sodium 'salt of the compounds vof ythis invention. In the AdrawA lng the fvarious symbols have the following meaning: Y

YV is the radical RICHalzSiCHz-f. i

R is an alkyl or monocyclic aryl hydrocarbon radical.

Rf isan .alkyl radical. I K Rfis an alkyl or .monocyolicarylhydrocarbon radical. n

X is a halogen atom.

-From the ralcove drawing `it can Alie-'seen that Y the synthesis of 'the `"ketosilanes,'depends upon the formation of a triorganosilyl :substituted acetoacetio ester. This 4compound may thenbe' reacted with an alkyl halide to introduce .an alkyllsubstituent.

The formation ofthefkettnesnomthe subv stituted sacetoacetic y'esters either with .or Without alkyl side. chains, 'may be V,accomplished by cleaving them `with :concentrated LHCl or a dilute alkali metal hydroxide solution.. ."Insuch event.

the vester group is cleaved to produce `a substituted ketone. Only those ketones .in which R is methyl may be prepared by this method.

Alternatively, vthe substitutediacetoacetic esters may 'be treated with sodium ethylate, lin which event cleavage ofthe keto group ftakes place.

to @produce a substituted ester. 'This ester is (Cl. 2GB-4448.2)

. .2 then :hydrolyzed to fa v,carboxylic acid which in turn 'is `converted Ato 'an `acyl `chloride by .treatment with thionyl chloride. The :acyl chloride is 'thenfconverted to a ketone fby treatment with `acadrnium compound. Bythisxmethod ketones in which R is any falkyl or monocyclic `7varyl radical can be prepared. Thus, a-.greater variety of products may be synthesized by the second method than by Athe rst. It is vto vbe Vnoted that the use of excess vsodium in the primary synthesis means that sodium -ethylate ispresent, and hence the substitution kof the acetoacetic ester and its cleavage occur in one operation.

The ketones of this invention undergo normal Sketone reactions with such reagents `-as alkyl magnesium halides. methylsilyl-Z-butanone .is treated `with methyl Ymagnesium bromide 'in ether and the resulting fproduct is hydrolyzed,

yEfu'JHaJ :SiCHzCHzCCHs l zCO-Il :is produced. This tertiary falco'hol 'is 'readily converted into .corresponding chloride .4 trimethylsilyl-Z-methyl-'Z-chlorobutane,

:by treatment .of the alcohol with concentrated Y HClat room temperature. The ketones .of this invention may also be Yreacted with NaOBr to give the corresponding carboxylic acid.

Compounds'which are Within the lscope of this :invention rare Y.those in which .R is .anyalkyl tor monocyclic Varyl hydrocarbon radical, R' is any alkyl radical or hydrogen, Vand R Vis .anyalkyl or monocyclic aryl hydrocarbon radical. In those cases where it is desired `to prepare siloxanes .'-from .the .ketosilanes 'of this :inventiomgtit is preferable that R be methyl or phenyl.

, The compounds of this'invention are useful yas Hsolvents and Vin some .instances .as intermediates in the preparation oi .silo'xanes. VThese :compounds A.also serve vas valuable additives for conventional .siloxanes The Viollowing examples .are villustrative .only and are not to be construed as limiting the invention, the yscope of which is properly delineated in the appended claims.

a lstirrer, .dropping Tunnel, and .redux condenser,

4sodium ethylate Aprepared by the .addition of 3U 'grams of sodium to 1 liter of absolute For example, When 4-triethanol. To this was added during 15 minutes 170 grams of ethyl acetoacetate, followed by the addition during 30 minutes of 300 grams of iodomethyltrimethylsilane. The solution was stirred and heated at reflux temperature for 30 minutes. The reaction components, boiling from 70 to 78 C., were removed by distillation and the residue was treated with water. The organicV layer was separated and the aqueous layer was extracted with three 300 cc. portions of ethyl ether. After drying over anhydrous sodium sulfate, the solvent was removed and the product was fractionated to give a 48% yield of ethyla-trimethylsilylmethylacetoacetate.

In a three-neck flask equipped with a stirrer and a reflux condenser there was placed 24 grams of ethyla-trimethylsilylmethylacetoacetata .80 cc. of concentrated HCl, and 80 cc. of ethanol.

The reaction mixture was stirred and heated at 90 C. for four hours. Ether was then added and the mixture was saturated with sodium chloride. After extraction of the aqueous layer with three 300 cc. portions of ether the combined organic layers were dried over sodium sulfate. Distillation of the organic layer gave a 59% yield of 4-trimethylsilyl-2-butanone Y I (CH3) aSiCHzCHzCOCI-Is] This compound boils at 84 C. at 65 mm. and was found 'to have the following properties: an 1.4228, d .833, and molar refraction of 44.

Example 2 dium sulfate and distillation, there was obtained.v

in 72.4% yield the compound ethyl-a-methyl-atrimethylsilylmethylacetoacetate.

This compound. was then refluxed with a 10% aqueous solution of sodium hydroxide. After separation of the organic layer and distilling,

The organic layer Was separated and the there wasY obtained in 53% yield the compound Y' 4-trimethylsilyl-3methyl-Z-butanone [(CHa) 3SiCH2CHCH3 COCHal This compound has the following properties: boiling point 83 C. at 40 mm., nD20 1.4280, d20 .836, and molar refraction 48.7.

Example 3 The compound 3-trimethylsilylmethyl-2-pentanone A CH3) 3SCH2CH(C2H5) COCI-Is] was prepared by the method of Example 2 exi cept that ethyl bromide was employed in the place of methyl iodide. The compound has the following properties: boiling point 88 C. at 30 mma 11.1320 1.4295, d20 .843, and molar refraction 52.8.

Example 4 500 grams of iodomethyltrimethylsilane Was addedl with stirring and refluxing during three minutes to sodioacetoacetic ester. The latter had been prepared by reacting 296 grams of acetoacetic ester with a 3% excess of sodium ethylate .4 in one liter of ethanol. The reaction mixture was heated at the reflux point for 14 hours. After cooling, the reaction product was neutralized with 15 cc. of glacial acid. The product was distilled to remove low boiling fractions and there was obtained ethyl acetate and unreacted iodomethyltrimethylsilane. The ethyl acetate resulted from the keto cleavage of the acetoacetic ester.

The product remaining after the removal of low boiling fractions was treated with Water and the organic layer was separated and the aqueous layer was extracted with three 300 cc. portions of ether. The combined organiclayers were dried over anhydrous sodium sulfate and fractionated to give 250 grams of ethyl--trimethylsilylpropionate.

A mixture of 246 grams of ethyl--trimethylsilylpropionate and 100 cc. of 10% sodium hy- `droxide solution were stirred and heated at C. for two hours. After cooling, the solution Was acidied with concentrated hydrochloric acid and the upper layer was separated. After drying over sodium sulfate, fractionation of the producty gave -trimethylsilylpropionic acid.

40 grams of -trimethylsilylpropionic acid was heated with 50.4 grams of thionyl chloride for one hour at 90l C. A distillation of the product gave -trimethylsilylproponyl chloride in 89% yield.

Diphenylcadrnium was prepared by adding at 0 C. over a period of ve minutes, 30 grams of cadmium chloride to an ether solution of phenylmagnesiumbromide. After removal of the major proportion of the ether by distillation, 300 cc. of benzene was added and an additional portion of ether was removed by heating on the steam bath. While heating the reaction flask on the steam bath there was added 21.5 grams of -dimethylsilylproponyl chloride over a period of five mini utes. After heating for an additional twenty. minutes, the reaction product was poured onto a mixture of HC1 and ice. The organic layer was then separated and lthe aqueous layer extracted with two cc. portions of benzene.- The combined organic layers were Washed with water, 5%

sodium carbonate solution, and finally with waterI After drying over sodium sulfate and distilling, 10 grams of 3-trimethylsilyl-l-phenyl--1-y tained. This compound has the following properties: boiling point C. at 4 mm., nD2 1.5085, d20 .955, and molar refraction 64.4.

Example 5 -phenyldirnethylsilylpropionic acid was prepared in the manner of Example 4, starting with phenyldimethyliodomethylsilane, acetoacetic ester, and sodium.

24 grams of -phenyldimethylsilylpropionic acid was heated with 58 grams of thionyl chloride at 90*7 C. for two hours.

chloride.

Dimethylcadmium was prepared by reacting methylmagnesiurn bromide in ether solution with cadmium chloride. The reaction was carried out vat a temperature of 0 C. and the cadmium chloride was added over a period of ve minutes. Most of the ether was removed and benzene was added. The dimethylcadmium solution was heated on a steam bath as 12.5 grams of phenyldimethylsilylpropionyl chloride was' added. The reaction mixture was then stirred and heated for one hour at 80 C. It was cooled and poured into ice water and the organic layer was separated. The aqueous layerwas extracted with two 200 cc.-

Fractionation of the product gave -phenyldimethylsilylpropionyl portions of benzene and the combined layers were Washed with aqueous potassium carbonate and then with Water. Upon fractionation there was obtained a 45% yield of 4-phenyldimethylsilyl- 2butanone, CsH5(CII3)2SiCH2CH2COCI-Is. This compound had the following properties: boiling point 109 C. at 4 mm., nD20 1.5065, d20 .963, and molar refraction 63.7.

That which is claimed is:

1. A compound of the formula in which R and R, respectively, are selected from the group consisting of alkyl and monocyclic aryl hydrocarbon radicals, and R is selected from the group consisting of alkyl radicals and hydrogen.

2. (CH3)3SiCH2CH2COCI-Is.

3. (CH3) aSiCH2CH(CH3) COCI-Ia.

5. CGI-I5 (CH3) 2SCI-I2CH2COCH3. 6. A method of producing ketosilanes which comprises reacting an ester of the formula CHSCOCR' [CHzSi (CH3) 2R] COzEtI with a reagent selected from the group consisting of concentrated HC1 and dilute aqueous alkali metal hydroxide solution whereby the COzEt group is cleaved to produce a ketone of the formula R(CH3) zSiCHzCI-IRCOCHa where R, in bo-th compounds is selected from the group consisting of alky1 and monocyclic aryl hydrocarbon radicals and R is selected from the group consisting of alkyl radicals and hydrogen.

7. (CI-Ia) 3SiCH2CH(C2H5) COCHs.

LEO H. SOMMER.

References Cited in the file of this patent Sommer et al., Jour. Am. Chem. Soc., vol. 72, (May 1950) pp. 1935-1939. 

1. A COMPOUND OF THE FORMULA R"COCHR''CH2SI(CH3)2R IN WHICH R AND R", RESPECTIVELY, ARE SELECTED FROM THE GROUP CONSISTING OF ALKYL AND MONOCYCLIC ARYL HYDROCARBON RADICALS, AND R'' IS SE- 